In a car environment, the longer you keep the signal digital the better, as there will be less opportunity for noise. And a digital amp means one less piece of gear you'll have to install, I think it's a good option if you haven't already invested in a non-digital amp(s). Most of them seem a little on the expensive side considering the power, but I suppose that's the cost of an all in one solution. The Phoenix Gold amp is cheap but has no power.

I wouldn't want to use the Creative product you linked to in particular, since it's not designed for automotive use, and probably has low voltage outputs. Maybe 2v? For me 4v is the minimum, and 9-13 is ideal. Panasonic, Claion, Alpine and Audiobahn all have DSPs with SPDIF inputs.

Isn't it a better idea to use a PROCESSOR or EQUALISER with optical input than to use an amplifier with optical input?

Surely a processor or equaliser is more likely than an amplifier to have high quality DACs inside. This would also allow you to use a wide range of amplifiers instead of being limited to just a small selection.

In short, I think it is a better idea to setup similar to how Defiler (above) has explained he is setting up.

I'm going to start a separate thread about which EQs have optical input. In my case I only want stereo sound, not digital surround.

There are several threads on that already. There's not many available, and you're probably going to end up with surround features whether you want them or not.

There's not much to a DAC. As long as it conforms to spdif specs, I wouldn't expect much of a difference between those found in an amp or an EQ. Although what is done to the signal afterwards will surely vary substantially. I'm still undecided on using software for EQ control instead of hardware, which I have to do since the ADD51t has limited equalizer functionality, but even the default Winamp EQ seems to be very effective at fine tuning. And I can have individual presets for every single song that auto load if I want, something I can't do in hardware.

The processor Defiler mentioned is indeed nice, but check out the price. And talk about unneeded features.

I got my Alpine unit off ebay for about $420. Yes a bit pricey and yes it will have features I probably will never use but the price was right and this is my fifth Carputer in my last four cars and each time I did something different/better. I always wanted 5.1 and figured this was the time to do it.

The main reason on my last Carputer I went with a hardware EQ/Preamp was I wanted instant control of volume/EQ settings without having to rely on the computer/touchscreen/remote. Just

I'm not bashing the Alpine unit, in fact I'd trade my setup for one in a heartbeat. $420 is a great deal, the best price I could find was $650 shipped for the processor and controller, and since I only wanted 4.1 for 95% music playback I just couldn't justify it.

The Audiobahn unit is basic, but I constantly use it for volume control, mute, and subwoofer control. Subwoofer control is one thing you have to do in hardware if you're using digital output: I don't want to constantly adjust the low end frequencies, but the voltage on the RCAs going to the sub amp, depending on the song. The ADD51T has the typical EQ presets, but I don't find them to be useful except for watching movies. Although I have made use of the bass and treble settings on occasion.

So unless I get an analog EQ or upgrade, I'm stuck with software. But having owned several dedicated 1/2 DIN and 1/4 DIN EQs with past setups, all Kenwood, I'm not missing anything. I would have to take my eyes off the road for just as long to adjust a band in hardware as I currently do in Road Runner. And with a single button press I can select one of my six custom presets, or allow for song/album presets.

I just got my carputer setup....and this is my first carPC. Before this I've always been the type to spend a lot of money on my audio equipment. I've gone through 5 different systems in my last car and about 2 in my current car. I feel that I had a decent setup before I went down the carPC route....I got a 2 channel 1600D excellon pushing my subs and a 5 channel excellon powering my insides. I feel that I was getting barely enough power to my subs if not just enough.

Well, after putting the pc in my car, things have changed. My system doesn't sound as clean anymore, and now that digital is an option, I think it should be utilized. It would be a shame to waste that option...its just that I'm concerned with power. It seems like none of the amps that I have seen that support 5.1 provide enough power to the sub channel (especially in my case since that would be divided among two subs).

Would it be possible to run two digital amps...one for speakers and one for the subs? IF I did this would I need an external digital pre-amp or DSP to split the signal for the sub's channel?

Also, is it necessary to have a digital signal going to the subs? Do they sound better digitally or is it mainly for the other four speakers? If not, is there a digital to analog converter that I can use it only on the sub channel so that I can keep my excellon amp powering my subs and avoid having to buy 2 digital amps?

Sorry for all the questions, but I think that digital is a must and was just exploring all the options...